> Could you please elaborate? I'm not experienced
> with MPI and I need to test a heterogenous
> installation, to see whether the computational
> task is actually broken down and computed in
> collaborative manner.
>

It sounds like you're asking an application-specific question.
Specifically, "how will my application behave in a heterogeneous
scenario?" That can really only be answered by your application.

All that Open MPI gives you is the ability to start up/shut down
processes and reliable messaging between them. How your application
decomposes the problem that it's solving and and distributes the load
between different machines is up to the application.